An energy storage system, or a battery system, typically includes a plurality of batteries or other energy storage devices coupled together to provide electric power for an application. The total energy of the system may be scaled up or down by increasing or decreasing the number of energy storage devices of the system. Energy storage systems, can be used in many applications. For example, an energy storage system having many batteries connected together may be used to provide power to buildings, machines, etc. In another example, an energy storage system may be used to power an electric vehicle. When the stored energy in the energy storage system decreases, the system may be recharged, for example, by using power from a utility grid and/or an internal combustion engine.
In energy storage systems where a plurality of batteries (or energy storage subunits) are coupled together, the amount of energy stored in the different batteries of the system may be, or become, different over time. That is, energy may be unevenly balanced between the different energy storage units of an energy storage system. Such an imbalance of stored energy can affect the efficiency, reliability, and output of the energy storage system. Embodiments of the current disclosure may address these and/or other problems in the art. The scope of the current disclosure, however, is defined by the attached claims, and not by the ability to solve any specific problem.